So I'm currently doing my social service and my lead told me to stop using python (Django REST Framework) to create the new API we need and use php instead, only because nobody else knows python in there...

Tbh it makes sense.
The cost of doing it in php vs the cost of everyone learning python sufficiently is a lot less.

We had a similar situation at work, where the most appropriate language for a project was Erlang. Learning curb would have been too much though, so we did an event loop in python.